Multiple outlet lubricating pump



Aug. 12, 1952 o. HAJEK MULTIPLE OUTLET LUBRICATING PUMP Filed Feb. 26, 1948 Q J MA H w T O BY K6 ATTOKNEY.

Patented Aug. 12, 1952 UNITED STATES Otto Hajek, Vienna, Austria, assignor to Alex. Friedmann Kommandit-Gesellschaft, Vienna,

Austria Application February 26, 1948, Serial No. 11,210 In Germany November 9, 1938 Section 1, Public Law 690, August s, 1946 Patent expires November 9, 1958 4 Claims.

This invention relates to a lubricating pump in which a delivery piston co-operates with a control piston in such a manner that it alternately supplies two outlets with lubricant, while both pistons are driven by cams, preferably through the medium of rocking levers, in such a manner that two piston movements of the appertaining delivery piston correspond to each piston movement of the control piston. Such lubricating pumps usually have a number of pump elements, each of which is equipped with a delivery piston and a control piston, by which pistons two outlets are alternately supplied with lubricant.

In such lubricating pumps the control pistons can be driven by means of circular eccentrics which engage in mouths of rocking levers which embrace the eccentrics with plane-parallel surfaces. At the same time the movement of each control piston relatively to that of its appertaining delivery piston must take place in such a manner that the appertaining delivery piston always completes a compression stroke when the control piston is just passing through a dead centre, and that when the control piston is passing through the middle position the appertaining delivery piston completes a suction stroke. In the one dead centre the control piston opens the passage from the workin chamber beneath the delivery piston to the one outlet of the pump element and in other dead centre opens the passage to the other outlet. In the middle position the control piston holds the suction aperture open, through which the delivery piston inspires the lubricant from the storage tank into its working chamber. In consequence of being driven by means of a circular eccentric, the control pistons reach their maximum speed just when they are passing through their middle position, and the period during which the suction apertures of the pump elements are held open is relatively short for a given driving speed. When a viscous lubricant is used, the latter therefore has insufficient time to fill the pump working chambers completely through the suction apertures. Thus the delivered amounts are reduced to an undesired extent, which impairs the lubricating performance and the accuracy of the pump delivery.

In orderto obviate this drawback it has already been proposed to use, instead of circular eccentrics for driving the control pistons, cams which were so shaped that the control pistons stand still for some time when passing through their middle position, and the opening time of the suction apertures was prolonged. In known designs of this type, however, the jaws of'the rocking 2 levers embrace the appertaining driving cams after the manner of tongs by means of two knife edges,'between which the appertaining cam lies in each of its positions without play.

Although this design enabled a temporary standstill of the control pistons while passing through the middle position to be obtained, so that sufficient time was allowed for the complete filling of the working chambers with lubricant during the suction strokes of the delivery pistons, another disadvantage was incurred. The knife edges of the rockin lever jaws wore out very quickly to such an extent that even after anundesirably short working time, so much play resulted between said knife edges and the driving cams of the control pistons that the positive movement of the control pistons was lost, and for this reason inaccuracy in the delivery action and finally a failure of the pump elements oc-- curred.

One object of the present invention is to obviate the foregoing disadvantages.

To this end, the invention consists essentially in that the driving cam, working between planeparallel jaw surfaces, for the control piston has a profile formed from arcs and/or curves in such a manner that the control piston comes to a standstill when passing through its middle position, or at least slows down its movement, and the cam is guided in all its positions without play between the plane-parallel jaw surfaces.

By suitably selecting the jaw width for the. rocking levers, i. e. by selecting the distance between the aforesaid plane-parallel surfaces, it is possible, by composing the peripheral profile of the appertaining driving cam of adjoining arcs, to form a cam which in every position lies without play between the plane-parallel surfaces and by the rotation of which the control piston is driven in such a mamier that it comes to a temporary standstill when passing through its middle position.

According to a feature of the invention, the profile of the cam operating the control piston is designed, in the regions lying against the jaw surfaces during the passage of the control piston through the middle position, with arcs of circles which are concentric with the cam axis and have equal radii, and, in the regions lying against the aw surfaces during the passage of the control piston through the dead centres, said profile is conveniently designed with arcs of circles which are concentric with the axis of the cam and which have radii which difier from one another by the amount of the stroke of the cam,"whi1e said arcs of circles are joined together by connecting arcs. At the same time the connecting arcs are preferably formed of arcs of circles. the centres of which lies approximately at the opposite points of transition from the arcs concentric with the cam axis to the connecting arcs.

The effect is achieved, through the design of the rocking lever jaw and the cam driving the control piston according to the presentinvention, that the jaw flanks co-operating with the cam, since they are plane surfaces with which cylindrical surfaces of the cam periphery co-operat, are now subjected to only very slight wear, so

that detrimental play between them and the cam surfaces can occur only after years of use;

Since the working flanks of the cams partly roll on the surfaces of the rocking jaw, further reduction of friction and hence of wear is obtained. On account of the temporary standstill of the control piston when passing through its middle-position, the filling of the working chamber. of v the pump elements by suction is always lubricants with which they previously could notcope.

In order to enable; the invention to be more readily understood, reference is made to the accompanyingadrawings which illustrate diagrammaticallyv and byway of example, one embodiment. thereof, and. in which- Fig. 1 is a section through a lubricating pump designed in accordance with the invention; and

Fig. 2 shows on an'enlarged scale the cam which serves: to; drive the control pistons The oil tank 1 contains the pump element 2 which hasa delivery piston 3 and a control piston 4-. The delivery piston. 3 is driven by means of a i'ocking. lever.5, which is mounted to rotate about a; pin- Brand is. set in' rockingmotion by a The end SJ double cam"! on the driving. shaft 8. of the lever=5zengages in the head lot the delivery piston- 3-. possibletoproduce backlash betweenthe arm end 9 and-the head l0;=and*thus toreduce the stroke ofthe'delivery piston 3 to the desired-extent.

Thecontrol'pistonfiis moved up and down by a;-rocking,.=;le,ve1- l2, which isalsomounted to rotate-about the pin-6 :andis rockedby the cam |3.--'

Said lever-l2 transmits its motion to the control pistonzd through its end l4, which engages .ina-

jaw on therpiston head- I5. The rocking-lever I2 embraces the cam- 13 by means of a jaw=composed of two plane-parallel surfaces l6 and'llh In consequence of the shape of the double camJ, the delivery. piston 3 performs two strokes: during-one revolution of the driving cam' B, while thecontrol piston 4, which is driven by the caml'3jshapecl asshown in Fig. 2, performs only one stroke, The positionof the two cams l and'l3- relatively ',to one another isso selected that when the delivery piston 3 is descending-the control piston 4 is. movingeither through the upper or throughjthelower dead centre, and during each rising stroke of the delivery piston 3 the control pistonjd is passingthrough its middle position,

L h h, ;by .virtu'e of. the hereinafter-described-i By means of a screw H it'is 4 shape of the driving cam l 3 appertaining thereto, it is temporarily brought to a standstill.

Each pump element 2 has two outlets l8 and I9, which are in communication with the working chamber 20 of the delivery piston 3 through passages 2| and 22 respectively. The lubricant is drawn from the tank I through the suction passage 23. For the control of the passages 2|, 22, and 23 the control piston 4 is provided with a groove 24.

In order toproduce the afore-described movements of the control piston, the profile of the cam [3, as shown in Fig. 2 is formed of four arcs ofcircles a-b, c--d', e and gh, which arcs have'their' centres in the aXis of rotation A of the driving shaft '8, and of four eccentric arcs bc, d-e,.ig, and 71-01, which constitute the working flanks of the cam l3. The arcs of circles a=b and e-f, which lie against the jaw surfaces I6, [1 during the passage of the control piston through it's'middle position, have the same radius, which correspondsto half the width of the jaw; Of the arcs-0f circles 0-22 and 9'-h, which lie" against the 'jaw' surfaces I6, I! while the control piston is in its dead centres, the circular arc c'd hasa radius that-is greater than that of the circular aren't-1L by the amount of the stroke of the cam. The connecting arcs bc, de, ,f-g, an'd h-a are-alsoformed by arcs of circles, the centres of "which lie approximately at the opposite points of 'transitionfrom the arcs concentric with the" cam 'axistotheconnecting arcs. The centre of the arc b-c lies approximately at the point of transition of'the arc' e-f into the-arc f--g, the

' centreof the arc of a circle-fg liesapproxi-' mately at'the point of transition of the arcb-c intothe arc c-'-d; and so on.

Inthe positionillustrated in Fig. 1, the control pi'ston- 4' is in'- itsm'iddle position and, through its groove 24, establishes communication from deadcentre; The groove2 3 in the-control pistons thus-releasesthe passage 2!; and during the subsequent downward stroke of the-delivery piston the lubricant is forced from the-chamberZO through the'passage'2l to the cutletlB; The

- control piston 5 then moves downwards, back intoits middle position, in which it stands still for some time and during which a'furthe'r suc tion stroke-of the delivery piston 3takespl'ace. Finally, the controlpiston l'then passes to its lower=-dead=centre, inwhich it frees communica tion'thioughtheflpassage 22 through its groove 28? During the subsequent downward 'stroke'of' the delivery piston the lubricant is delivered" from the space 26 through the passage 22 toth .ou-tlet i9,--whereupon the'control piston da'g'ain' returns-to its' middle position,- and the afc-i'e described cycle-of operations is repeated.

As-long as the-arcs ab'an'd e' 'or"thecam l3' are-ir'1 contact with the jaw surfaces l6 and l!- of the=rocking-lever l2, the latter is not moved; and-the-controlpiston 4; whichis then in its middle position, stands still, sotha't even viscous" lubricant has sufiic'ient time to pass through the suction-1 aperture 23 and the groove Zfiinto" the" space'z2ll beneath. the 'deliverypiston 3k When? the eccentric working flanks bc and f-g or d-e and h-a come into contact with the jaw surfaces [6 and I1, the rocking lever [2 is turned. The individual arcs are arranged to follow one another in such a manner that the cam l3 lies in all its positions without play between the plane-parallel jaw surfaces 16 and I! of the rocking lever I2, The movement of the control piston 4 is therefore completely positive and, by virtue of the circumstance that plane surfaces of the jaw always co-operate with the cylindrical surfaces of the cam l3, friction remains within such bounds that even after lengthy use no play occurs between the cam I3 and the jaw surfaces I6 and I? through wear. No rubbing knife edges or other edges are present, which might result in rapid wear. On rotation of the driving shaft 8, moreover, the working flanks b--c and f-g, and d-e and h-a. of the cam l3 partly roll on the plane jaw surfaces 16 and I 7, whereby a further reduction of friction and hence of wear on the cam I 3 and on the jaw surfaces [6 and l I is achieved.

What I claim is:

1. In a lubricating pump of the type comprising a pump chamber having two outlets and an inlet disposed therebetween, a pump piston in said chamber for drawing lubricant through said inlet and delivering it to said outlets, a control piston having a throat for controlling said inlet and outlets, a shaft, two elbow levers swingably supported by said shaft, said levers individually having an arm individually connected with one of said pistons, a rotating cam engaging the other arm of the lever whose one arm is connected with the pump piston, for oscillating the lever for reciprocating the pump piston; the other arm of the lever, whose one arm is connected with said control piston, having two prongs, each prong having an inside surface parallel to the inside surface of the other prong, a rotating cam disposed between said surfaces and having a cam surface comprising two substantially diametrically opposed cylindrical portions of like radii centered substantially at the rotation axis of the cam, having two other diametrically opposed cylindrical portions concentric with the rotation axis of the cam, the radii of the said other portions differing from one another by the stroke of the cam, and having four convex portions individually interposed between said cylindrical portions.

2. In a lubricatin pump of the type comprising a pump chamber having two outlets and an inlet disposed therebetween, a pump piston in said chamber for drawing lubricant through said inlet and delivering it to said outlets, a control piston having a throatfor controlling said inlet and outlets, a shaft, two elbow levers swingably supported by said haft, said levers individually having an arm individually connected with one of said pistons, a rotating cam engaging the other arm of the lever whose one arm is connected with the pump piston, for oscillating the lever for reciprocating the pump piston; the other arm of the lever, whose one arm is connected with said control piston, having two prongs, each prong having an inside surface parallel to the inside surface of the other prong, a rotating cam disposed between said surfaces and having a cam surface comprising a first pair of substantially diametrically opposed cylindrical portions of like radii centered substantially at the rotation axis of the cam, a second pair of cylindrical portions disposed on a diameter which is at a right angle to the diameter on which the first pair of cylindrical portions is disposed, the radii of the cylindrical portions of the second pair differing from one another by the stroke of the cam, a third pair of cylindrical portions individually interconnecting the large radius portion of the second pair and one portion of the first pair, and a fourth pair of cylindrical portions individually interconnecting the small radius portion of the econd pair and one portion of the first pair.

3. In a lubricating pump as set forth in claim 2, the lengths of the radii of the cylindrical portions of each of the third and fourth pairs being equal.

4. In a lubricating pump as set forth in claim 2, the portions of the third pair individually centering substantially at the line of intersection of the opposed portion of the fourth pair and a portion of the first pair, and the portions of the fourth pair individually centering substantially at the line of intersection of the opposed portion of the third pair and the large radius portion of the second pair.

OTTO HAJEK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain 1939 

